I have a string like this String str = "la$le\\$li$lo".
I want to split it to get the following output "la","le\\$li","lo". The \$ is a $ escaped so it should be left in the output.
But when I do str.split("[^\\\\]\\$") y get "l","le\\$l","lo".
From what I get my regex is matching a$ and i$ and removing then. Any idea of how to get my characters back?
Thanks
Use zero-width matching assertions:
String str = "la$le\\$li$lo"; System.out.println(java.util.Arrays.toString( str.split("(?<!\\\\)\\$") )); // prints "[la, le\$li, lo]" The regex is essentially
(?<!\\)\$ It uses negative lookbehind to assert that there is not a preceding \.
Simple sentence splitting, keeping punctuation marks:
String str = "Really?Wow!This.Is.Awesome!"; System.out.println(java.util.Arrays.toString( str.split("(?<=[.!?])") )); // prints "[Really?, Wow!, This., Is., Awesome!]" Splitting a long string into fixed-length parts, using \G
String str = "012345678901234567890"; System.out.println(java.util.Arrays.toString( str.split("(?<=\\G.{4})") )); // prints "[0123, 4567, 8901, 2345, 6789, 0]" Using a lookbehind/lookahead combo:
String str = "HelloThereHowAreYou"; System.out.println(java.util.Arrays.toString( str.split("(?<=[a-z])(?=[A-Z])") )); // prints "[Hello, There, How, Are, You]" 
$ is the first character, my regex can still split on it, and yours can't, because it insists that there is a character preceding it (that is not a slash).The reason a$ and i$ are getting removed is that the regexp [^\\]\$ matches any character that is not '\' followed by '$'. You need to use zero width assertions
This is the same problem people have trying to find q not followed by u.
A first cut at the proper regexp is /(?<!\\)\$/ ( "(?<!\\\\)\\$" in java )
class Test { public static void main(String[] args) { String regexp = "(?<!\\\\)\\$"; System.out.println( java.util.Arrays.toString( "1a$1e\\$li$lo".split(regexp) ) ); } } Yields:
[1a, 1e\$li, lo]
You can try first replacing "\$" with another string, such as the URL Encoding for $ ("%24"), and then splitting:
String splits[] = str.replace("\$","%24").split("[^\\\\]\\$"); for(String str : splits){ str = str.replace("%24","\$"); } More generally, if str is constructed by something like
str = a + "$" + b + "$" + c Then you can URLEncode a, b and c before appending them together
import java.net.URLEncoder.encode; ... str = encode(a) + "$" + encode(b) + "$" + encode(c) 
import java.util.regex.*; public class Test { public static void main(String... args) { String str = "la$le\\$li$lo"; Pattern p = Pattern.compile("(.+?)([^\\\\]\\$)"); Matcher m = p.matcher(str); while (m.find()) { System.out.println(m.group(1)); System.out.println(m.group(2)); } } } gives
l a$ le\$l i$ 
String str = "la$le\$li$lo"? do you meanString str = "la$le\\$li$lo"??